app/views/layouts/_dev_debug.html.erb
<div id="debug">
<%= link_to "params", '#', "data-toggle-id" => "params_debug_info", :class => 'toggler' %> |
<%= link_to "session", '#', "data-toggle-id" => "session_debug_info", :class => 'toggler' %> |
<%= link_to "environment", '#', "data-toggle-id" => "env_debug_info", :class => 'toggler' %> |
<%= link_to "request", '#', "data-toggle-id" => "request_debug_info", :class => 'toggler' %>
<fieldset id="params_debug_info" class="debug_info" style="display:none">
<%=debug(params) %>
</fieldset>
<fieldset id="session_debug_info" class="debug_info" style="display:none">
<%=debug(session) %>
</fieldset>
<fieldset id="env_debug_info" class="debug_info" style="display:none">
<%=debug(request.env) %>
</fieldset>
<fieldset id="request_debug_info" class="debug_info" style="display:none">
<%=debug(request) %>
</fieldset>
</div>